1. Field of the Invention
The present invention is directed to a fuel injection valve comprising a valve housing including a valve housing body which has a valve seat provided on an inner surface at a front end thereof and a fuel injection hole centrally opening into the valve seat. A valve member is contained in the housing body and is seatable onto the seat. A cap is positioned in the front end of the valve housing body and has a pair of diverging injection holes diverging from each other in a forward direction from a junction positioned in front of the fuel injection hole. The valve housing has air supply passages for supplying assist air to the fuel flow injected from the fuel injection hole.
2. Description of the Prior Art
Fuel injection valves have been conventionally known, for example, as shown in Japanese Patent Application Laid-open Nos. 43962/84 and 362272/92.
In the fuel injection valve disclosed in above Japanese Patent Application Laid-open No. 43962/84, a pintle is integrally connected to a valve member, so that the fuel is atomized by the pintle. In addition, the atomization is enhanced by an assist air from air supply passages. However, the pintle has an enlarged portion at its tip end, and hence, the fuel from the fuel injection hole collides against the enlarged portion, so that the fuel spray flow is spread. This results in a relatively large amount of fuel being deposited on an inner surface of the valve cap. For this reason, if the amount of assist air from the air supply passages is relatively small, the particle size of the fuel spray flow from the fuel injection valve is relatively large.
In the fuel injection valve disclosed in Japanese Patent Application Laid-open No. 362272/92, in addition to the atomization of the fuel by the collision of the fuel spray flow from the fuel injection hole against a junction, the atomization is promoted by the assist air from the air supply passages. Therefore, good atomization can be achieved even when the amount of assist air supplied is relatively small, but a variation in rate of distribution to the pair of diverging injection holes is liable to be produced due to the turbulence of a beam-like spray of the fuel from the fuel injection hole.